import sys
from collections import deque
# sys.stdin = open('input.txt', 'r')
input = sys.stdin.readline
h, w = map(int, input().split())
empty, fox, rabbit = 0, 1, 2
mapping = {'.': empty, 'F': fox, 'R': rabbit}
grid = []
for _ in range(h):
grid.append([mapping[x] for x in input().strip()])
# add padding!
grid.append([0]*len(grid[0]))
for row in grid:
row.append(0)
queue = deque([(0, 0)])
curr_color = grid[0][0]
grid[0][0] = 0
color_cnt = 1
other_color_cnt = 0
ans = 0
while queue:
i, j = queue.popleft()
# if not grid[i][j]: # already visited
# continue
# curr_color = grid[i][j]
# grid[i][j] = 0 # mark visited
for ni, nj in ((i+1, j), (i-1, j), (i, j+1), (i, j-1)):
if grid[ni][nj]:
if grid[ni][nj] == curr_color:
queue.appendleft((ni, nj))
color_cnt += 1
else:
queue.append((ni, nj))
other_color_cnt += 1
grid[ni][nj] = 0
color_cnt -= 1
# print(color_cnt)
# when we run out of the current color in the bfs queue (or when it 0/1 bfs switches from 0 to 1)
if not color_cnt:
color_cnt = other_color_cnt
other_color_cnt = 0
curr_color = not (curr_color-1) + 1 # switch the color
ans += 1
print(ans)
